Condensation of aluminum chloride, a subliming solid, has been difficult. A number of publications describing aluminum chloride condensed in particular ways to form a bulk aluminum chloride that can be added as a solid to a reduction cell have been published. However, in spite of this there are more recent proposals describing specific methods for handling the problem of feeding aluminum chloride to an aluminum reduction cell.
The high temperature of the cell and the high surface area of aluminum chloride, which is extremely hygroscopic, make it imperative that an effective cell addition method be devised, since the introduction of a hydrated aluminum chloride even in small amounts is considered undesirable in aluminum chloride cell operation.